In recent years a variety of food products in which dietary fibers effective for improving bowel movements and preventing adult diseases are incorporated are available on the market. The dietary fibers incorporated in such food products are mainly composed of hardly water-soluble dietary fibers. Hardly water-soluble dietary fibers mostly pass through the digestive tracts without being digested and absorbed, inducing increased amount of stools, so that the rectum is physically stimulated to increase a desire to defecate and the stools are softened to improve bowel movement. They are therefore effective in proctosenous constipation.
Constipation, however, is frequently of mixed type of proctosenous and colonic ones. For the colonic type of constipation (atonic) with reduced peristalsis, readily water-soluble fibers are more effective, because they are hydrolyzed in the lower digestive tracts by intestinal microorganisms and the hydrolysis products, organic acids, activate peristalsis of digestive tracts thereby accelerating defecation although they are not hydrolyzed by human digestive enzymes.
Therefore, it is desirable to take both of the hardly water-soluble dietary fibers and the readily water-soluble dietary fibers for effectively preventing or curing constipation.
Japanese Patent Application Laid-Open-to-Public No. 262572/1985 discloses food products comprising hardly water-soluble dietary fibers coated with readily water-soluble dietary fibers. However, because of low contents of the readily water-soluble fibers in such food products, they are not effective in colonic constipation.
Approximately two third of the fecal amount is water and the water content is especially dependent upon undigested food, especially the content of dietary fibers. Therefore, ingestion of the hardly water-soluble dietary fibers of high water-retention more effectively increases the amount and water content of stools.